1. Being in favor of guns is incompatible with being in favor of life.
2. Being in favor of the death penalty is incompatible with being in favor of life.
3. All those who are pro-life are necessarily in favor of the death penalty and guns.
I can dispute 1 and 3 on the spot.
Some opponents of gun control assert that guns keep people safe. Outlawing guns would have little effect on criminals' access to guns. Since criminals tend to disregard the law, anyway, they would get their guns in spite of the law. The average, law-abiding citizen, however, would have trouble obtaining a gun. Since he would have no gun, he would be more vulnerable to the criminal, who has a gun. Loosening gun laws would allow the average law-abiding citizen to have a gun, as well, and the criminal would have no advantage. In this sense, guns can be seen as an equalizer -- they put the victim on level ground with the criminal. As such, the first premise can be reconciled with being in favor of life.
I can dispute the third premise simply by stating that I am pro-life and am not in favor of the death penalty.
Keep the big picture in mind. I am not arguing for less gun control or for pro-life. I am disputing your assertion that pro-life is a religious argument. Even if your second statement did imply the first, it wouldn't matter, since your second statement relies on faulty premises.